`sig
type t
val compare : Cf_tai64n.t -> Cf_tai64n.t -> int
val now : unit -> Cf_tai64n.t
val first : Cf_tai64n.t
val last : Cf_tai64n.t
val compose : Cf_tai64.t -> int -> Cf_tai64n.t
val decompose : Cf_tai64n.t -> Cf_tai64.t * int
val to_unix_time : Cf_tai64n.t -> float
val of_unix_time : float -> Cf_tai64n.t
val to_label : Cf_tai64n.t -> string
val of_label : string -> Cf_tai64n.t
val add : Cf_tai64n.t -> float -> Cf_tai64n.t
val sub : Cf_tai64n.t -> Cf_tai64n.t -> float
end`